A selective filtration system for an operator cab attached to an agricultural vehicle. A HVAC unit supplies conditioned air to an operator space selectively from a CAT 4 filter and a CAT 2 filter. A pressurization blower and two way valve controls flow from the CAT 4 filter to the HVAC unit. Control of flow or isolation of the CAT 2 filter is provided by pressure variations within the system. The CAT 4 filter and CAT 2 filter are isolated from the ambient when they are not in use by valves. A calibrated orifice enables positive pressurization to the CAT 2 filter to hold the valves closed.

A filter device of a motor vehicle may include a step filter, two flow paths, and a plurality of adjustable air flaps. The step filter may include a plurality of individual filter elements arranged fluidically in series. A first flow path may extend through at least two individual filter elements. A second flow path may extend through a number of the plurality of individual filter elements which, compared to a number of the plurality of individual filter elements through which the first flow path extends, may be reduced by at least one single individual filter element. The plurality of adjustable air flaps may be arranged at least one of upstream and downstream of the step filter. At least one air stream may be guidable through the step filter along at least one of the first flow path and the second flow path via the plurality of adjustable air flaps.

A filter element for filtering a fluid has a frame and at least one filter bellows arranged in the frame and provided with a first areal inflow surface for a first fluid flow and at least one second inflow surface for a second fluid flow separate from the first fluid flow. The second inflow surface is separate from the first areal inflow surface. A flow channel is provided to guide the second fluid flow and has a raw-side flow channel section arranged within the frame. A filter system provided with a filter housing is provided with such a filter element arranged exchangeably in the filter housing between a raw side and a clean side. The filter housing has a first inlet for the first fluid flow communicating with the first inflow surface and at least a second inlet for the second fluid flow communicating with the second inflow surface.